Enduring Understanding:

• Humans use energy from a variety of sources, resulting in positive and negative consequences.

Learning Objective:

• Describe the use of hydroelectricity in power generation.

• Describe the effects of the use of hydroelectricity in power generation on the environment.

Essential Knowledge:

• Hydroelectric power can be generated in several ways.  Dams built across rivers collect water in reservoirs.  The moving water can be used to spin a turbine.  Turbines can also be placed in small rivers, where the flowing water spins the turbine.

• Tidal energy uses the energy produced by tidal flows to turn a turbine.

• Hydroelectric power does not generate air pollution or waste, but construction of the power plants can be expensive, and there may be a loss of or change in habitats following the construction of dams.

Sources

Dams and Reservoirs

• Relies on the kinetic energy of moving water

• The reservoir is is the body of water contained behind the dam

• The intake is the opening into the narrow ‘penstock,’ where water flows and gains speed

• It then flows past a turbine, turning it, and generating electricity

• The water flows past unaffected and continues into a river or another body of water

Micro Hydropower

• Small scale

• Water is taken into an intake but transported in pipes through the penstock

• The powerhouse is right on the bank, water flows through then empties back into the main river

• Off the grid but same process

Tidal Power

• Uses the same principles, but in the ocean

• The current or tides turn the turbine which generates electricity

Advantages and Disadvantages

Benefits

• No air pollution

• No waste

• Relatively inexpensive electricity generation

• Additional services provided be reservoir

Drawbacks

• Flooding of land to make reservoir

• Disruption to flow rates of river

• High maintenance cost for tidal

• High construction cost for dams

• Most viable sites are already used

Environmental Concerns

• There is a ton of habitat destruction or at least change when reservoirs are created

  • Disrupting the flow of water creates massive changes, happening to rapidly that natural adaptation cannot keep up

• Fish migrations are also disrupted

  • In North America there have been some investments in ‘fish ladders’ where the fish can gently move up without encountering any of the turbines or mechanics